<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    function calculate(method,...nums){
        let result;
        if(!method || nums.length == 0){
            alert('请传入参数');
            return;
        }
        if(method == '*' ){
            result = 1;
            for(let i =0;i<nums.length;i++){
                result *= nums[i];
            }
        }else if(method == '+'){
            result=0;
            for(let i=0;i<nums.length;i++){
                result += nums[i];
            }
        }
        alert(result);
    }
    calculate("+",1,2);//3
    calculate("+",1,2,3,4,5);//15
    calculate("*",1,2,3);//6
    calculate("*",1,2,3,4,5);//120

</script>
</html>